Intake Air Temperature Control System

1. Ensure all vacuum hoses and the stove to the air cleaner flexible connector are properly installed and in good condition.
2. With engine cold, and ambient temperature in the engine compartment below 65°F on 1982-85 4-97.4/1.6L 4-105/1.7L, 4-135/2.2L and 1986-87 4 cylinder carbureted engines, 84°F on 4-156/2.6L engines, 50°F on 6 and V8 engines or 115°F on 1986-87 4 cylinder engines with fuel injection, the heat control door in the snorkel should be in the up (heat on) position.
3. With the engine warmed to operating temperature and running, check the air temperature entering the snorkel or at the sensor. When temperature is 85°F or higher on 1982-85 4-97.4/1.6L 4-105/1.7L and 4-135/2.2L engines, 113°F or higher on 4-156/2.6L engines, 100°F or higher on 6 and V8 engines, 90°F or higher on 1986-87 carbureted 4 cylinder engines or 140°F on 1986-87 4 cylinder fuel injected engines, the door should be in the down (heat off) position.
4. Remove air cleaner from engine and allow engine to cool down to 65°F on 1982-85 4-97.4/1.6L 4-105/1.7L, 4-135/2.2L and 1986-87 4 cylinder carbureted engines, 84°F on 4-156/2.6L engines, 50°F on 6 and V8 engines or 115°F on 1986-87 4 cylinder engines with fuel injection. Using a suitable vacuum pump, apply 20 inches Hg vacuum, on all engines except 4-156/2.6L engine, to the sensor. On 4-156/2.6L engine, apply 15 inches Hg vacuum to the sensor. The door should be in the up (heat on) position. If not, check vacuum diaphragm.
5. To check the vacuum diaphragm, apply vacuum directly to the diaphragm, with a vacuum gauge in the line and bleed valve to control the vacuum inserted in the line between the gauge and the vacuum source. Apply 20 inches Hg vacuum to the diaphragm on all 4 cylinder engines, except 4-156/2.6L and 1982-83 6 and V8 engines. On 4-156/2.6L engines, apply 10 inches Hg vacuum to the diaphragm. On 6 and V8 engines, apply 25 inches Hg vacuum to the diaphragm. On all engines except 4-156/2.6L engine, the diaphragm should not bleed off more than 10 inches of vacuum in 5 minutes. On 4-97.4/1.6L 4-105/1.7L, 4-135/2.2L and 4-153/2.5L engines, the door should not lift off the bottom of the snorkel at less than 2 inches Hg vacuum and should be in full up (heat on) position with no more than 4 inches Hg vacuum. On 1982-83 6 and V8 engines, the door should not lift off the bottom of the snorkel at less than 5 inches Hg vacuum and should be in full up (heat on) position with no more than 9 inches Hg vacuum. On 1984-87 6 and V8 engines, the door should not lift off the bottom of the snorkel at less than 5.5 inches Hg vacuum and should be in full up (heat on) position with no more than 8.5 inches Hg vacuum. On 4-156/2.6L engines, with 10 inches Hg vacuum applied to the diaphragm, the door should be in the full up (heat on) position. If diaphragm does not operate properly, replace diaphragm.
6. If the diaphragm performs properly but proper temperature is not maintained, replace the sensor and repeat procedure.